The storage of electronic data is one of the most important aspects of the digital age as consumers and businesses increasingly rely on persistent, efficient and reliable access to this necessary data. Because of the importance of this data, a variety of methods and systems have been developed to provide redundant and efficient data access to ensure the availability of the data.
Redundant arrays of independent disks (RAID) have been provided to ensure such data availability. RAIDs may include multiple storage devices having mediums for storage of electronic data and depending on the protocol used, data may be obtained even in the event of failure of one of the storage devices. However, the amount of storage needed by a user may require that a data storage apparatus be specially configured to provide the desired throughput and storage quantity.
For instance, in a smaller environment, a singe RAID may be provided having redundant storage devices for storage of all the information necessary for a small business. In an enterprise solution, vast arrays of storage systems may need to be provided, having pluralities of controllers, storage devices, and caches.
Between the enterprise solutions needed by large businesses and a single RAID used by small businesses and individuals are mid-range solutions. Many mid-range RAID solutions rely on pairs of controllers operating dependently to both increase performance and add redundancy. Typically each controller will own a unique set of logical unit numbers, and operate somewhat autonomously. Another characteristic of mid-range solutions is that, typically, multiple caches are employed, such as one for each controller. These caches must be periodically synchronized with one another so that each controller may be prepared to take over partner LUNs in the event of a controller failure. Such synchronization may require specialized resources within the storage device and consume valuable apparatus resources, thereby making the solution more expensive and less desirable.
Therefore, it would be desirable to provide a system and method for cache management for storage controllers.